The inventors of the present invention devised a method and apparatus for regulating the transport of a preselected ion across a cell membrane utilizing an applied, oscillating magnetic field. This remarkable achievement is disclosed in U.S. patent application Ser. No. 923,760 entitled, "Techniques for Enhancing the Permeability of Ions", which was filed on Oct. 27, 1986, and the disclosure of which is incorporated herein by reference. Therein, a method and apparatus are disclosed by which transmembrane movement of a preselected ion is magnetically regulated using a time-varying magnetic field tuned to the cyclotron resonance energy absorption frequency of the preselected ion. This important discovery brought to light the interplay of local magnetic fields and the frequency dependence of ion transport mechanisms.
Having established a method by which selective ion transport can be regulated, the present inventors discovered that certain characteristics of living tissue could be controlled by application of an oscillating magnetic field having a non-zero average value. Significantly, it was determined that selected ratios of the frequency of the applied field to the flux density of the total magnetic field passing through the tissue along a predetermined axis were capable of stimulating the growth and developnent of the target tissue. This was demonstrated to be effective in promoting the growth of bone tissue. As a result, U.S. patent application Ser. No. 172,268, entitled "Method and Apparatus for Controlling Tissue Growth with an Applied Fluctuating Magnetic Field" was filed on Mar. 23, 1988, the disclosure of which is incorporated herein by reference.
Therein, there is provided an apparatus for controlling the growth of living tissue. The apparatus includes magnetic field generating means such as a field coil for generating a controlled, fluctuating magnetic field which penetrates a tissue, and an associated magnetic field sensing device for measuring the intensity of the magnetic field present in the tissue. In one embodiment, the magnetic field generating means and magnetic field sensor are enclosed within a housing along with a power source.
The work with tissue growth control was extended and it was discovered that tissue development can be regulated to control the growth characteristics of non-osseous, non-cartilaginous connective tissue proper and cartilaginous tissue. These inventions are disclosed, respectively, in U.S. patent application Ser. No. 254,438, entitled "Method and Apparatus for Controlling the Growth of Non-Osseous, Non-Cartilaginous Solid Connective Tissue", which was filed Oct. 6, 1988, the disclosure of which is incorporated by reference, and in U.S. patent application Ser. No. 265,265, entitled "Method and Apparatus for Controlling the Growth of Cartilage", which was filed Oct. 31, 1988, the disclosure of which is incorporated by reference.
The inventors have now discovered that by using a feedback system to monitor the local field component of the composite magnetic field, the applied component can be automatically adjusted to maintain the proper balance to bring about transmembrane movement of ions in any application of ion transport tuning.